1. Field of the Invention
The present invention relates generally to a hammering tool, and more particular to a hammering tool with an adjustable nail-drawing device.
2. Description of the Related Art
Conventional claw hammers include a shaft and a metal hammer head. User may hold the shaft to hammer objects by the hammer head. The hammer head includes a column-like hammer portion and a claw portion at a rear thereof. The claw portion has a V-shaped claw to draw nails. To draw a nail out of an object, such as wood plate, user has to engage the claw with the nail. In such condition, the claw hammer works like a lever, the claw is resistance, the top of the hammer head, which touches the object, is fulcrum and the shaft is effort, so that user may exerts the shaft to lever the nail out.
Typically, the claw has a limited slope relative to the top of the hammer head, such that the nails only may be drawn out for a predetermined distance. In other words, only shorter nails may be totally drawn out of the object by the claw hammer. For the longer nails, the claw hammer only draw half of it out of the object, and user has to take other tool, such as pliers, to draw the nail out.
Many inventions, such as U.S. Pat. No. 4,422,620 and U.S. Publication No. 2005/0017225, are presented to overcome above drawback. The first invention provides a hammer with a bolt screwed in the top of the hammer head. The bolt is screwed to adjust the height of the bolt, such that the hammer may draw the nail for longer distance when the bolt is screwed with greater height. The second invention's hammer is provided with a bolt embedded in the hammer head. The bolt is moved between two positions, in one of which the bolt is protruded out the hammer head, and in another of which the bolt is received in the hammer head. Both of inventions provide the bolt screwed in a threaded hole of the hammer head. The threads of the bolt or the thread hole may be broken when the hammer is levering the nail by the claw. When the threads are broken, the bolt may be jammed in the thread hole or may be loosed that the hammer loses the adjustable nail-drawing function.